Catadromous Species

The thin-lipped grey mullet displays a great adaptation capacity to different habitats. They can occur from saline coastal waters to freshwater river stretches. Juveniles under 3 cm feed on zooplankton. After that, this species presents a great feeding plasticity throughout their life, with microphytobenthos and sediment rich in organic matter as major diet components. This species occurs in all river basins, from Minho to Guadiana. The spawning period takes place in coastal areas from late autumn to early winter. Upstream migration occurs in the spring from March to June. The main threats to this species include habitat eutrophication (reduces fertility), and changes to salinity and hydrological regime.

The European eel prefers habitats that offer refuge and readily available hiding places. This is an omnivorous species, and larger specimens may feed on smaller fishes. It occurs in all Portuguese river basins from Minho to Guadiana, and in coastal waters of the Azores and Madeira archipelagos. The European eel is a semelparous species that spawns in the Sargasso Sea. The larvae drift with the oceanic currents to the continental shelf, where they metamorphose into glass eels and enter continental waters. Migration to continental waters takes place between October and March. Main threats are poaching, overfishing (particularly in the glass eel stage), loss of river continuity and increasing spreading of the parasite Anguillicoloides crassus